MIRAI MR12-05 Leg2 Expendable Bathythermograph (XBT)

Last Modified: 2017-06-29
: MR12-05 Leg2
: Processed (DMO)-QCed
: JAMSTEC
: Depth, Temperature
:
OCEANS > OCEAN TEMPERATURE > WATER TEMPERATURE

For Using Data

Data Management Office
See Terms and Conditions about constrain of use.
See Terms and Conditions about data citation.
Instrument:
Expendable bathythermograph (XBT) (MR11-04 - )
Using XBT (eXpendable Bathy Thermograph) system, the vertical distribution of water temperature is observed during free fall of its probe part in the seawater. On board, the analogue signal is converted to the temperature by data processor and the data is stored in PC. Depth data is calculated from the elapsed time.

(1) Launcher
Hand launcher
Manufacturer : Sippican,Inc.
Type : LM-3A
Operation area : Rear upper deck

Automatic launcher
Manufacturer : Tsurumi Seiki Co., LTD.
Type : AL-8
Location : Port side of rear (4m from the sea level). The control panel is installed in the investigation room.

(2) Converter
Manufacturer : Tsurumi Seiki Co., LTD.
Type : MK-30N
Location : Investigation room
Sampling rate : 50 msec

(3) XBT probe specifications
Probe type TSK T-5 TSK T-6 TSK T-7 TSK T-10
Temperature range [deg-C] -2.22 to 35.55
Temperature accuracy [deg-C] +/- 0.2
Measurment depth [m] 1830 460 760 300
Depth accuracy [m] 5 or +/- 2% of depth;whichever is larger
Maximum elapsed time [sec] 291 73 123 48
Rated ship speed [knot] 6 15 15 10
Coefficient-a 6.828 6.691 6.691 6.301
Coefficient-b -1.82 -2.25 -2.25 -2.16
Since XBT carries no pressure sensor, we need to estimate depth from the elapsed time. The fall-rate equation is as follows.

Z = at + 10E-3 * bt^2

Where Z(m) is the depth and t(sec) is the elapsed time.

In addition, coefficients of the fall-rate equation are different by XBT types.

Probe type TSK T-5 TSK T-6 TSK T-7 TSK T-10
Coefficient-a 6.828 6.691 6.691 6.301
Coefficient-b -1.82 -2.25 -2.25 -2.16
* Coefficients listed above are supplied by Sippican, Inc., in USA.

The list of an XBT type used in each cast is as follows.

Cast name XBT type
201212260936 T-7


(1) For sensor's stablility, values of less than 1 m for temperature are replaced by missing values, respectively, based on manufacturer's recommendation.

(2) Quality control
QCed data were added flag according to the NODC (National Oceanographic Data Center) quality control procedure.
1) The gradient check of adjacent depth data
2) The broad range check set up at given ocean space and depth
Please see the site of NODC of the following link for quality control procedure in detail.
In addition, an abnormal value is identified by a visual check, and the data after visual QC is released.
(1) It is reported that T-5 probes produced by Tsurumi Seiki Co. Ltd. (TSK T-5 probes) have a fall-rate bias. Please see the following about fall-rate bias corrected data.

Related Information

Update History

2017-06-29
An observation data was registerd.
2015-05-21
An observation data was registerd.
2015-01-15
An observation data was registerd.